RFR(L) 8136930: Simplify use of module-system options by custom launchers

[Daniel D. Daugherty]

Sounds good to me. Thanks!

Dan


On 7/20/16 1:48 PM, harold seigel wrote:
> Hi Dan,
>
> This was discussed today and it was decided the the JVM will issue 
> warnings if these specific properties are specified on the command 
> line, provided that option PrintWarnings is TRUE.  This will probably 
> be done as a separate bug.
>
> Thanks, Harold
>
>
> On 7/20/2016 3:42 PM, Daniel D. Daugherty wrote:
>> On 7/17/16 5:05 PM, harold seigel wrote:
>>> Hi,
>>>
>>> Please review these Hotspot VM only changes to process the seven 
>>> module-specific options that have been renamed to have gnu-like 
>>> names.  JDK changes for this bug will be reviewed separately.
>>>
>>> Descriptions of these options are here 
>>> <http://openjdk.java.net/jeps/293>.  For these six options, 
>>> --module-path, --upgrade-module-path, --add-modules, 
>>> --limit-modules, --add-reads, and --add-exports, the JVM just sets a 
>>> system property.  For the --patch-module option, the JVM sets a 
>>> system property and then processes the option in the same way as 
>>> when it was named -Xpatch.
>>>
>>> Additionally, the JVM now checks properties specified on the command 
>>> line.  If a property matches one of the properties used by one of 
>>> the above options then the JVM ignores the property. This forces 
>>> users to use the explicit option when wanting to do things like add 
>>> a module or a package export.
>>
>> Based on conversations with Harold, the JVM will _silently_ ignore the
>> specific properties if they are specified on the command line. Silently
>> ignoring the properties will likely lead to bugs being filed even if we
>> put a line or two in a man page somewhere. It seems useful for us to
>> issue a warning or an error if the user tries to specify properties on
>> the command line that we don't want to be specified.
>>
>> I poked around the bugs and I don't see a rationale for the silently
>> ignore behavior. Can someone please explain?
>>
>> Dan
>>
>>
>>>
>>> The RFR contains two new tests.  Also, many existing tests were 
>>> changed to use the new option names.
>>>
>>> JBS Bug: https://bugs.openjdk.java.net/browse/JDK-8136930
>>>
>>> Webrev: http://cr.openjdk.java.net/~hseigel/bug_8136930.hs/
>>>
>>> The changes were tested with the JCK lang and VM tests, the JTreg 
>>> hotspot tests, and the RBT hotspot nightlies.
>>>
>>> Thanks, Harold
>>
>